The present invention relates to a device for bending an extremity of a torsional spring. More particularly, the present invention relates to a device for bending an extremity of a torsional spring so that said bent extremity of the spring may be used with a plug, such as the ones used for operatively connecting torsional springs to overhead shafts of counterbalancing mechanisms of garage doors and the like.
It is known in the art that large, vertical, cable-operated doors, such as commercial and residential sectional garage doors, usually require counterbalancing mechanisms to counterbalance the weight of the door in order to decrease the force required to open the door and also facilitate its closing from a raised to a lowered position. Large sectional garage doors used in commercial and residential applications may be manually or power operated. In either case, but particularly for manually operated doors, counterbalancing mechanisms have been used for many years to counterbalance the weight of the door and control its opening and closing movements so that one person can easily control the operation of the door. Counterbalancing mechanisms are also advantageous for power operated overhead doors since they reduce the power requirements needed for the motor and they lower the structural strength required for the door opening and closing mechanism. In other words, lighter weight, lower cost, door controlling mechanisms may be used if a counterbalancing mechanism is connected to the door to assist it in its opening and closing movements. Furthermore, the provision of a counterbalancing mechanism minimizes the chance of a rapid and uncontrolled closing of the door in the event of a failure of the door opening and closing mechanism, which can result in serious injury or damage.
It is also known in the art that a widely used type of counterbalancing mechanism generally comprises a pair of spaced apart cable drums connected to flexible cables, each cable being in turn connected to a lower opposite side edge of the garage door. The cable drums are usually mounted on an overhead shaft which is supported above the door opening and is connected to one or more torsion springs which are each fixed to the shaft at one end, and secured to a fixed structure, such as the wall for example, at the other end, so that the cable drums are biased to rotate in a direction which winds the cables onto the drums and counteracts the weight of the door connected to the cables. The torsion springs are adjusted to properly balance the weight of the door so that minimal opening and closing efforts are required, either manually or when motor controlled.
It is also known in the art that conventional, low cost adjustment devices used for the above-mentioned type of counterbalance mechanism, and widely utilized in the garage door industry, are generally cylindrical xe2x80x9ccollarsxe2x80x9d commonly referred to also as xe2x80x9cplugsxe2x80x9d (or xe2x80x9cconesxe2x80x9d) which are connected to the so-called fixed ends of the torsion springs and are thus mounted on the aforementioned shaft for adjusting the deflection of the springs to preset the counterbalance force. The aforementioned plugs usually include one or more setscrews which lock the plugs to the shaft to prevent rotation thereabout except during normal adjustment of the spring deflection. The plugs also usually include sockets for receiving winding bars whereby the springs are manually preset, or xe2x80x9cpreloadedxe2x80x9d, by rotating the plugs with respect to the shaft using the winding bars and then locking the plugs to the shaft with the setscrews. Each plug may also include a slot onto which a corresponding bent free end of the torsion spring is hooked on. These slots are usually T-shaped, and are thus commonly known as xe2x80x9cT-slotsxe2x80x9d. An example of a known winding plug is shown in FIG. 11.
Typically, the shape of the slots of the plugs known in the art allows the introduction of the spring""s tail without the use of any tool. Once the spring tail is introduced into the slot of the plug, both the plug and the spring are then introduced onto a shaft and installed on site, after which the plug is pushed towards the spring and then rotated around the spring axis in order to have the spring tail blocked there by the slot of the plug. The combined slot and shaft hold the assembly together without any other accessories. An example of a conventional torsional spring hooked onto a known winding plug mounted onto a shaft of a counterbalancing mechanism according to the prior art is shown in FIG. 12.
An important problem associated with the aforementioned type of counterbalancing mechanism, or with any other type of counterbalancing mechanism which uses plugs for operatively connecting torsional springs to overhead shafts of counterbalancing mechanisms, is that the plugs require the torsional springs to have bent extremities which act as xe2x80x9chooksxe2x80x9d so as to be able to be mounted onto the slots of said plugs, i.e. so as to be able to be hooked onto the plugs. Therefore, it would be useful to provide a device would be able to bend an extremity of a torsional spring so that said bent extremity of the spring may be used with a plug of a counterbalancing mechanism.
Another important problem associated with the aforementioned type of counterbalancing mechanism, or with any other type of similar counterbalancing mechanism, is that the spring tail often requires to be bent in a particular manner, generally towards the center axis of the torsional spring and with the bent portion having a certain length, so as to be able to properly cooperate with a given plug of the counterbalancing mechanism. Therefore, it would be useful to provide a device which, by virtue of its design and components, would enable to bend an extremity of a torsional spring in a particular manner so that the bent extremity may properly cooperate with a plug of a counterbalancing mechanism.
Yet another important problem associated with the aforementioned type of counterbalancing mechanism, or with any other type of similar counterbalancing mechanism, is that a garage door installer often has to change or adjust torsional springs on site but is not always equipped with the appropriate equipment necessary to suitably heat and bend the spring extremities of a torsional spring because this equipment is generally quite heavy to carry around and fairly elaborate to operate. Therefore, it would be useful to provide a device which, by virtue of its design and components, would enable an easier, simpler and more cost effective way of bending an extremity of a torsional spring. It would be also useful to provide a device for bending an extremity of a torsional spring, which would not require the use of heat for bending the spring tail, and which would be easily transportable from one site to another.
Another important problem known in the art is that different methods and devices are generally required to bend the extremities of torsional springs having different wire sizes, i.e. torsional springs made of wires whose diameters are different. Therefore, it would be very useful to provide to a single device which, by virtue of its design and components, would be able to bend the extremities of torsional springs having different wire sizes.
Hence, in light of the aforementioned, there is a need for an improved device for bending an extremity of a torsional spring destined to be employed with plugs of counterbalancing systems of garage doors and the like. There is also a need for a device which, by virtue of its design and components, would enable to bend an extremity of a torsional spring in a particular manner so that the bent extremity may properly cooperate with a plug of a counterbalancing mechanism. Furthermore, there is also a need for a device which, by virtue of its design and components, would provide an easier, simpler and more cost effective way of bending an extremity of a torsional spring. Moreover, there is also a need for a device for bending an extremity of a torsional spring, which would not require the use of heat for bending the spring tail, and which would be easily transportable from one site to another. Moreover, there is a need for a device which would enable to bend an extremity of a torsional spring in a more cost effective way than what is possible with what is known in the art. There is also an important need for a device which, by virtue of its design and components, would be able to bend the extremities of torsional springs having different wire sizes.
The object of the present invention is to provide a device for bending an extremity of a torsional spring, which satisfies some of the above-mentioned needs and which is thus an improvement over the devices known in the prior art.
In accordance with the present invention, the above object is achieved with device for bending an extremity of a torsional spring, the device comprising:
a base plate;
at least one flange projecting from the base plate;
at least one bulge projecting from the at least one flange;
a lever arm pivotally mounted onto the at least one flange about a first pivot axis, the lever arm being operable between first and second positions; and
at least one cam pivotally mounted onto said lever arm about a second pivot axis, said at least one cam having a contact surface being positioned for operatively cooperating with said at least one bulge;
wherein the extremity of the torsional spring is inserted between the at least one bulge and the contact surface of the at least one cam when the lever arm is in the first position; and wherein said extremity is bent about the at least one bulge by the contact surface of the at least one cam when said contact surface is urged towards said at least one bulge and forced about the same over the extremity as the lever arm is operated into the second position.
Preferably, each cam is eccentrically mounted about the second pivot axis.
Preferably also, the lever arm is provided with a slot for receiving a winding bar.
Preferably also, the device comprises first and second flanges projecting from the base plate, the lever arm being pivotally mounted between said flanges about a shaft extending through corresponding bores provided on the flanges.
Preferably also, the shaft has first and second ends protruding from the first and second flanges respectively, said first and second ends acting as first and second bulges; and wherein the device comprises first and second cams, each of said cams being pivotally mounted on either side of the lever arm about a shaft extending through a corresponding bore provided on the lever arm, the first and second cams having each a contact surface being positioned for operatively cooperating with the first and second bulges respectively.
Preferably also, the cams are provided with biasing means for maintaining the cams in a biased position with respect to the lever arm.
The objects, advantages and other features of the present invention will become more apparent upon reading of the following non-restrictive description of a preferred embodiment thereof, given for the purpose of exemplification only with reference to the accompanying drawings.